Reduced interferon (IFN)-α conditioned by IFNA2 (-173) and IFNA8 (-884) haplotypes is associated with enhanced susceptibility to severe malarial anemia and longitudinal all-cause mortality

Severe malarial anemia (SMA) is a leading cause of pediatric morbidity and mortality in holoendemic Plasmodium falciparum transmission areas. Although dysregulation in cytokine production is an important etiology of SMA, the role of IFN-α in SMA has not been reported. As such, we investigated the relationship between IFN-α promoter polymorphisms [i.e., IFNA2 (A-173T) and IFNA8 (T-884A)], SMA, and functional changes in IFN-α production in children (n = 663;>36 months) residing in a holoendemic P. falciparum transmission region of Kenya. Children with SMA had lower circulating IFN-α than malaria-infected children without severe anemia (P = 0.025). Multivariate logistic regression analyses revealed that heterozygosity at-884 (TA) was associated with an increased risk of SMA [OR 2.80 (95 % CI 1.22-6.43); P = 0.015] and reduced IFN-α relative to wild type (TT; P = 0.038). Additional analyses demonstrated that carriage of the-173T/-884A (TA) haplotype was associated with increased susceptibility to SMA [OR 3.98 (95 % CI 1.17-13.52); P = 0.026] and lower IFN-α (P = 0.031). Follow-up of these children for 36 months revealed that carriers of TA haplotype had greater all-cause mortality than non-carriers (P>0.001). Generation of reporter constructs showed that the IFNA8 wild-type-884TT exhibited higher levels of luciferase expression than the variant alleles (P>0.001). Analyses of malaria-αssociated inflammatory mediators demonstrated that carriers of TA haplotype had altered production of IL-1β, MIG, and IL-13 compared to non-carriers (P>0.050). Thus, variation at IFNA2-173 and IFNA8-884 conditions reduced IFN-α production, and increased susceptibility to SMA and mortality.